1. Field of Invention
This invention pertains to a notification system for alerting a patient to adjust a mask utilized for treatment of sleep apnea. More particularly, this invention pertains to a notification system for detecting changes in airflow and/or air pressure as indicative of mask dislodgement by a sleeping patient during treatment of obstructive sleep apnea.
2. Description of the Related Art
Patients suffering from obstructive sleep apnea and central sleep apnea are typically treated with a device generating air flow having positive airway pressure (hereinafter PA pressure) that is delivered by a hose connected to a mask positioned over the nose or over the nose and mouth of a patient suffering from sleep apnea. The PA pressure of the air flow can be delivered as continuous positive airway pressure (hereinafter CPAP), as bi-level airway pressure with increased air pressure during inspiration (hereinafter BiPAP), or as variable airway pressure delivered to the mask. Many patients have difficulty tolerating the mask fitted to the patient's face during an entire night of treatment for sleep apnea. Typically, the patient will experience a sleep arousal period or will partially awaken to move about during the night, and will return to sleep without reapplying the mask. Frequently, the mask will be remain partially or fully removed by the patient with no recollection of adjusting or removing the mask. The effectiveness of the CPAP treatment for sleep apnea is significantly disrupted after the mask is partially or fully removed by the patient during sleep or during a brief waking event. A repetitive reminder system is needed to alert the patient that the mask should be readjusted or reapplied to the patient.
Prior pressure support systems typically provide a flow sensor that detects a decrease in the rate of air exhaust attributed to tube blockage and/or mask exhaust port occlusion. The decreased rate of air exhausted from a patient's mask is compared by prior support systems with an alarm threshold for a predetermined time period in order to determine if an alarm system threshold is triggered in order to alert a care-giver. After inspection and clearing of the air tube, and/or adjustment of the fit of the mask, the care-giver is typically required to reset the alarm signal. For home treatment of sleep apnea, a care-giver may not be available for immediate receipt of the alarm signal, or the care-giver may be asleep. It is most efficient to issue an alarm directly to a patient upon mask disruption.
Other prior pressure support devices typically provide an air flow sensor and an air pressure sensor that are located at the blower end of a hose connected to provide CPAP to a nose or mouth mask. The prior devices typically detect excessive mask leaks due to mouth breathing in order to provide an electronic log of the total time the device is used by the patient, whether the patient was breathing normal, whether apnea events occurred, and whether open mouth breathing occurs during the sleep cycle. It is preferred that an alarm be issued to the sleeping patient, thereby alerting the patient that his/her mask is dislodged as soon as possible after dislodgement in order to have the mask refitted and to maximize CPAP treatment of apnea throughout the sleep cycle.
To further maximize the effectiveness of sleep apnea treatment utilizing CPAP or a similar treatment, it is preferred that an alarm system provides a rapid alert to a patient when the mask is displaced during each sleep period. Issuance of an alarm directly to the patient is preferred upon detection of an increased air flow or a decreased air pressure to the mask.
A notification system is needed for detection of each disruption of positive airway pressure channeled to a mask adapted to supply positive air flow to a patient's airway during sleep apnea treatment. It is preferred that a notification system issues an alert response to the patient when one or more sensors detect significant changes in air flow or air pressure which are indicative of the mask being displaced from the patient's face.